Iterative image reconstruction in image-guided radiation therapy

Abstract

Reconstruction of projection images of a CBCT scan is performed by generating simulated projection data, comparing the simulated projection data to the projection images of the CBCT scan, determining a residual volume based on the comparison, and using the residual volume to determine an accurate reconstructed volume. The reconstructed volume can be used to segment a tumor (and potentially one or more organs) and align the tumor to a planning volume (e.g., from a CT scan) to identify changes, such as shape of the tumor and proximity of the tumor to an organ. These changes can be used to update a radiation therapy procedure, such as by altering a radiation treatment plan and fine-tuning a patient position.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS[0001]The present application is a continuation of International Application No. PCT / US2016 / 056539, filed Oct. 12, 2016, which claims benefit and priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 62 / 242,967, filed Oct. 16, 2015, the entire contents of which are herein incorporated by reference for all purposes.BACKGROUND[0002]In radiation therapy, a treatment plan is first determined. The patient is typically imaged using computed tomography (CT), and the resulting data is used to determine a treatment plan of one or more treatment sessions, potentially over multiple days. It is important to have the patient in a specific position during treatment that matches the position in which the planning CT was taken. But, the CT machine is different than the radiation treatment machine, and thus there are difficulties in obtaining accurate matching positions. To address this problem, some techniques perform image-guided radiation th...

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Benefits of technology

The patent describes methods for making computer systems more secure. The technical effects of this invention involve improving the ability of computer systems to protect sensitive information from being accessed by unauthorized individuals or malicious software.

Problems solved by technology

But, the CT machine is different than the radiation treatment machine, and thus there are difficulties in obtaining accurate matching positions.

Such volume-based position corrections using current CBCT techniques can sometimes account for only large errors in patient position through manual correction, but are otherwise limited due to lower image quality compared to diagnostic CTs.

And sometimes, current CBCT techniques may fail to help in patient positioning when imaging soft tissue.

All of the technical differences lead to worse soft tissue discrimination in the abdominal and pelvic regions for CBCT images.

And, due to such limitations, patient positioning is still the exclusive main use case, and thus the use of imaging to guide radiation therapy has been limited.

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